6HemeNon-erythroidErythroidHaemoglobinHaemoproteinsElectron transfer and energy trappingmyoglobinCytochromesOthers
7Porphyrins synthesisMitochondrionCytosolSpontaneousURO ICOPRO I
8ALA synthase + Water-soluble D-ALA Excreted in urine ALA dehydrase GlycineALA synthase+NH2-CH2-COOHWater-solubleExcreted in urineD-ALAALA dehydrasePBG deaminaseWater-solubleExcreted in urinePBGHydroxymethylbilane
9HydroxymethylbilaneURO III synthaseSpontaneousURO ICOPRO IURO IIIdecarboxylaseUroporphyrinogen IIIWater-solubleExcreted in urineLess water-solubleExcreted in urine/fecesCoproporphyrinogen III
10CORPO IIICOPRO oxidaseProtoporphyrinogen IXPoor water-solubilityExcreted in fecesPROTO oxidaseProtoporphyrin IXFerrochelataseHeme
22Sunnybrook Health Sciences Center Sampling Guide Hepatic Porphyrias (normal RBC Porphyrins)Erythropoietic Porphyrias ( RBC Porphyrins)Acute Intermittent Porphyria (AIP)Congenital Erythropoietic Porphyria (CEP)Variegate porphyria (VP)Erythropoietic Protoporphyria (EP)Hereditary Coproporphyria (HCP)Porphyria Cutanea Tarda (PCT)Presentation:PorphyriasTests to orderSampleAcute symptomsAIP1. Urine Porphyrin Precursors Screen & QuantitationRandom (50 ml) or 24-h with Tartaric acidAcute symptoms + skin lesions (may occur independently)VPHCP2. Feces Porphyrins Screen & QuantitationRandomSkin lesionsPCTCEPEP3. Urine Porphyrins Screen & Quantitation4. RBC Porphyrins Screen & QuantitationRandom (50 ml) or 24-h with Na2CO3Lavender-top (EDTA) blood; need HctNotes:At time of acute attack:1. Collect a random urine sample first (50 ml with no preservatives), before attempting to collect a 24-h sample.2. Request "Porphyrin Precursors" (ALA & PBG) instead of "Porphyrins" screen and quantitation. The Laboratory will have to adjust pH to 4-6 for "Porphyrin Precursors", but pH 8-10 for "Porphyrins". - The commonest problem causing confusion!3. All sample containers should be covered with tin foil to shield off from light.
26CASEA boy, average hematologic parameters over the subsequent 3 years were as follows:Mean corpuscular volume (MCV), 67 fL →microcyticIron studies were unremarkable →Defect in:Porphyrin synthesisHeme synthesisGlobin synthesisHemoglobin (Hb) level, 70.0 g/L;Mean corpuscular hemoglobin level, consistently < 20 pg;Reticulocyte counts ranged from 3.6% to 6.7%;
27A physical examination revealed scars on the face, hands, and forearms photosensitive bullous dermatosisThe diapers exhibited brilliant pink fluorescence when illuminated with long-range ultraviolet light. → Photosensitive porphyrin ringsFluorescent red cells were detected using a microscope fitted with a 405 nm light source. → CEP or EPA 50-mL urine sample contained 2003 ug uroporphyrin (normal, trace); 92% of this was uro-I. → CEPErythrocyte UROS activity was 21% of the normal mean. Collectively, these findings confirmed the diagnosis of CEP.
28Erythrocyte UROS activity was normal in both parents, an unexpected finding as obligate carriers (heterozygotes) for UROS mutations generally have half-normal enzymatic activity.UROS was sequenced, and no mutations or deletions were found in thechild or the parents.A GATA1 point mutation was found in the child at codon 216, changing arginine to tryptophan (R216W), as well as on 1 of the 2 GATA1 alleles of his mother and maternal grandmother.GATA1 gene, at Xp11.23, encodes a transcription factor, GATA bindingfactor 1 (GATA-1), that is critical for normal erythropoiesis, globingene expression, and megakaryocyte development.GATA-1 also regulates expression of UROS in developing erythrocytes.